The Doodlebug is a dull brown but, it has a similar shape to other Flint Beetles. Flies swarm around it and it has green feet.
Nintendo Player's Guide Description
They look as harmless as Female Sheargrubs, but Doodlebugs can cause a lot of trouble by emitting poisonous gas. If you manage to hit one of the scurrying critters with a Pikmin lob, it'll flip over and leave a pool of nectar. You can capsize a Doodlebug three times before it disappears.
"While life-forms that excrete foul musks to warn of danger are not rare, the doodlebug is the only species known to release flatulence when active above ground. Interestingly enough, since it is merely releasing the gas created by decay of the contents of the creature's intestines, it does not have a special musk-producing organ. This means the creature is in fact merely flatulating. Spectral analysis of the rank gas indicates it contains not only methane, but hydrogen sulfide as well, making the flatulence a Grade XIII biohazard."
"Looking for a flavor that will surprise and delight your guests? This beast's aroma may surprise your guests, but it won't be delightful!"
In order to kill it, Olimar must spray ultra-bitter spray at it and if the Pikmin attack it, it gets destroyed. Doing so does not produce a spray.